The knee Flashcards
meniscal injuries
Give me some relevant anatomy?
relevant biomechanics?
Causes of Injury?
Anatomy:
- vascular in peripheral third (were inflammation occurs most)- better healing potential
- minimal innervation except periphery
Biomechanics:
-Menisci move anteriorly during extension and posteriorly during flexion
Injury causes:
- impact with a twist
- sports that require frequent pivoting with ass. Valgus/ varus forces
- Knee instability can cause secondary meniscal tears
- chronic ACL insufficiency
- far more common mon medial meniscus (larger surface area, more weight bearing, less mobile)
- meniscal injury take form of tear m.c: Anterior horn, posterior horn, bucket handle.
Medial meniscal injury sings and symptoms:
- acute (traumatic) or insidious (especially MCL and ACL sprain/ tear)
- locking, catching, giving way (quadriceps inhibition)
- effusion (swelling)- dependant on location of tear, haemarthrosis may be present
- tears in outer third more likely to cause swelling due to vascular nature of peripheral menici
- LIGAMENTOUS injury will cause significant often instantaneous effusion
- locking–> occurs in significant tears with loose bodies (OCD)- which prevents the last 20-30deg of extension
- true locking is subtle and only picked up with force passive extension and meniscal lesion may cause painful springy block. Pseudo-locking occurs with hamstring spasm.
- Exam findings: Join effusion 50% of cases (often persistent), medial joint space tenderness, reduce painful hyper flexion/ hyperextension depending on location of lesion.
Pes anserine conjoins what tendons?
- sartorius
- gracilis
- semitendonosus
What is the O’Donahues triad?
Whats the long term implications?
Treatment?
- medial meniscus, ACL and MCL concurrently injured
- meniscal tears shown to accelerate hyaline cartilage loss and can therefore go not to lead to compartmental OA (injury creates OA)
- conservative to surgical (arthroscopic) partial or complete (total) meniscectomy –> contributes to increased load bearing across the articular surfaces proportionate to amount of meniscus removed.
Meniscal Cysts
- A meniscal cyst is a well-defined cystic lesion located along the peripheral margin of the meniscus, a part of the knee, nearly always associated with horizontal meniscal tears.Assosiated with horizontal cleavage tears but can occur in isolation
- Occurs due to trauma (often compressive) or degeneration
- More frequently lateral
- Frequently asyptomatic in themselves may increase or reduce with extension and flexion
Osteochondritis Dissecans (OCD)
What is it?
Clinical presentation?
Possible causes?
- Disorder of one or more ossification centres, characterized by sequential degeneration or aseptic necrosis and recalcification
- Lesions involve both bone and cartilage, most commonly femoral condyles (medial 85%, lateral 10%) and then posterior surface (5%)
- Av age 10-20yrs but can occur in any age group
- Male> Female ratio→ 2-3: 1
- Bilateral involvement in 30-40% of cases
- Difficult to distinguish initially from acute traumatic osteochondral fractures and sometimes meniscal injuries
- OCD causes 50% Of loose bodies in the knee
• Clinical presentation
o Poorly localized ache within the knee (‘it hurts somewhere in my knee’
o Possible clicking or popping, or even locking if loose body
o Varying degrees of pain, swelling and stiffness
o Giving way of knee may occur secondary to quads weakness
o Prolonged symptoms lead to secondary OA
o May get fluctuant effusions- ie knees okay until I go for a run-then it swells and stiffens.
• Possible causes
o Trauma
o Vascular causes/ ischemia
o Skeletal maturation (accessory centers of ossification)
o Genetic conditions
o Metabolic factors
o Hereditary factors
o Anatomic variation
Give me some applied anatomy on the ligamentous structures of the knee
Types of Instability in Knee:
- anteromedial- what structures would be compromised>
- anterolateral
- posterolateral
- posteromedial
- At full knee extension, ACL and PCL both taut
- ACL develops more tension
- PCL twice as as strong as ACL
- ACL limits ANT tibial glide
- PCL limits POST tibial glide
Types of instability at the knee:
o Lateral, medial, anterior, posterior
• Types of instability (rotary or complex)
o Anteromedial- ACL; MM
o Anterolateral- ACL; LM- medial meniscus, MCL
o Posterolateral-PCL, LM (look for rotation of tibia on posterior component)
o Posteromedial- PCL, MM
ACL injury what is it MOI treatment clinical presentation
• Main resistance to anterior tibial glide
• Most frequent cause of haemarthrosis in the knee → rapid onset, it stabilizes the joint as it increases capsular tension
o Differential Diagnosis of capsulitis, juvenile rheumatoid, septic arthritis, medial meniscal tear( slow onset of haemarthrosis)
• MOI→Hyperextension injury, especially if hamstrings aren’t firing
o Low-velocity, non-contact, deceleration injury OR contact injury with a rotational component
o Highly innervated and has substantial proprioceptive role
• Treatment tailored to what activity patient wishes to return to.
• Clinical Presentation:
o Audible ‘pop’ present at time of injury
o Haemarthrosis develops rapidly- usually large
o Significant pain and instability
PCL injury
Wht happens?
clinical presentation?
• PCL thought to be primary stabilizer of the knee (thus rarely injured in isolation)
• Primary function: stop posterior translation
• Injury much less common than ACL (broader and stronger than the ACL)
• Injury happens m.c when force applied to anterior tibia when knee is flexed (eg dashboard injury)
o Hyperextension and rotational or varus/valgus stress mechanisms also responsible for PCL tears
• Clinical presentation:
o Pain and haemarthrosis much less than for ACL
o Posterior tibial sag visible
MCL Injury
MOI
- M.c injured ligament in knee ranging from sprain to tear
- MOI- valgus force, external tibial rotation
- Semimembranosus muscle, pes anserine muscles, and vastus medialis provide dynamic stability
LCL injury
- LCL and popliteus work together to limit varus opening, external rotation and posterior translation of tibia
- Popliteus→ posterior knee pain when crouching, running or walkinh downhill or going downstairs (when knee actively flexed in weight bearing)
MFPDS and Knee Pain
What would cause anterior and anteromedial knee pain?
Inferomedial knee pain
- Anterior and Anteromedial Knee pain: Rectus femoris, vastas medialis, Sartorius, gracilis, adductors longus + brevis
- Inferomedial Knee pain→ Pes anserine
Compare and contrast haemarthrosis and Effusion
Haemarthrosis Indicates significant intra-articular pathology Usually ACL injury Also seen in MM injury Presents as tense, inflamed knee
Effusion
General reaction to stress on knee
Common in chronic conditions (chronic meniscus, OA)
Usually slow and recurrent
ITB Friction Syndrome
Clinical presentation
Examination findings
- Its essentially a tendonisis and common cause of lateral knee pain
- Esp in cyclists and runners (repetitive knee flexion/ extension)
- During flexion, ITB moves posteriorly along lateral femoral condyle
- TFL hypertonicity most likely cause
- The bursae normally protect the tendon
• Clinical presentation
o Lateral knee pain, may radiate
o Worse running downhill
o M.c patients experience pain only during activities
o Treat→ lengthen ITB, make sure gluts, vastas lateralis all lose, and adjust pelvis?
Examination findings
o Tenderness over lateral femoral condyle
o Pain can be elicited with active flexion- extension of the knee within the first 30deg while the thumb presses over epicondyle and ITB
o Crepitus may be felt
Acute knee dislocation.
tell me about it
tell me about how to prevent it?
• Usually at least ACL and PCL torn entirely (primary constrains of the knee)
• Hard signs of vascular injury such as distal ischemia often present
• Surgical intervention with adequate rehab is essential
• If they have significant haemarthrosis needs to be drained to stop neurovascular compromise
• Sometimes taping and bracing ankle can predispose knee to injury
Prevention of Injury: The best prevention is a well conditioned athlete with properly strengthened and balanced quadriceps and hamstring muscles and good flexibility.
